PHP preg_replace() Function Usage and Example

PHP Regular Expression (PCRE)

The preg_replace function performs a search and replace operation using a regular expression.

Syntax

mixed preg_replace ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit =　-1　[, int &$count ])

Search for the part of subject that matches pattern and replace it with replacement.

Parameter Description:

• $pattern: The pattern to be searched, which can be a string or an array of strings.

• $replacement: The string or array of strings to be used for replacement.

• $subject: The target string or array of strings to be searched and replaced.

• $limit: Optional, the maximum number of replacements allowed for each subject string per pattern. The default is-1(Unlimited).

• $count: Optional, indicates the number of replacements performed.

Return value

If the subject is an array, preg_replace() returns an array; otherwise, it returns a string.

If a match is found, the subject after replacement is returned. Otherwise, the original subject is returned. If an error occurs, NULL is returned.

Online example

<?php
$string = 'google';　123,　456';
$pattern = '';/(\w+) (\d+), (\d+)/i';
$replacement = 'w3codebox ${2},$3';
echo preg_replace($pattern, $replacement, $string);
?>

The execution result is as follows:

w3codebox　123,456

<?php
$str = 'nho o o';
$str = preg_replace('/\s+/', '', $str);
//　will be changed to 'w3codebox
echo $str;
?>

The execution result is as follows:

w3codebox

<?php
$string = 'The quick brown fox jumped over the lazy dog.';
$patterns = array();
$patterns[0] = '';/quick/';
$patterns[1] = '';/brown/';
$patterns[2] = '';/fox/';
$replacements = array();
$replacements[2] = 'bear';
$replacements[1] = 'black';
$replacements[0] = 'slow';
echo preg_replace($patterns, $replacements, $string);
?>

The execution result is as follows:

The bear black slow jumped over the lazy dog.

<?php
$count = 0;
　
echo preg_replace(array('/\d/', '/\s/'), '*', 'xp　4　to',　-1　, $count);
echo $count;　//3
?>

The execution result is as follows:

xp***to
3

PHP Regular Expression (PCRE)